Im reading binary file, storing the data into arrays, and then writing the data
into another file. Basicly, a copy. Everything was fine, but then suddenly, out
of nowhere, the output file was corrupt. the size of the output is exact like
the input, however, if loaded in Quakespasm (Q1 engine) it crashed with
Hunk_alloc failed.
proc AddLump*(lumpnum: int32; data: pointer; len: int32) =
var lump: ptr lump_t
lump = addr(header.lumps[lumpnum])
lump.fileofs = c_ftell(wadfile).int32
# lump.fileofs = getFilePos(wadfile).int32
lump.filelen = len
echo header.lumps[lumpnum], " lump.fileofs ", lump.fileofs, "
lump.filelen ", lump.filelen
writeBuffer(wadfile.addr, data, (len + 3) and not 3) # this comes from C:
fwrite(wadfile, data, (len+3)&~3)
Run
After pulling my hair couple of hous, thinking its some ptr array leak in other
procs, it narrowed down to the I/O.
I changed getFilePos with:
proc c_ftell(f: File): int64 {.
importc: "ftell", header: "<stdio.h>", tags: [].}
Run
and everything went back to normal.
However, if I used "_ftelli64" version, the output was same as with getFilePos,
empty bytes inbetween blocks, and wrong offsets.
How is this possible, when i didnt touch anything in the read/write procs? I
didnt change the compiler, gcc or nim.
